Question - Generating Links from World Points

[chitalian]

Hi, I am pretty new to this all. But I was wondering if someone could help me. I have a set of world coords for different joints and I have been trying to build chains for these points however I am having trouble figuring it out.

Here is an example:

{
'left_leg': ([-23.4254, -23.5361, -23.9642], # X-points
              [-4.2424, -4.2233, -4.3618], # Y-Points
              [1.0065, 0.5614, 0.6598]), # Z-Points
}

Where we would have three joints all connect like this

joint_0 = (-23.0585, -4.3753, 0.208) joint_1 = (-23.0799, -4.3955, 0.6677) joint_2 = (-23.3939, -4.4256, 1.0013)

The end goal is to simulate a human's leg and solve for toe position.

Thanks for your help in advance!

[Phylliade]

Hello @chitalian,

If you want to create a chain by yourself, you need to create the chain from a list of Link.

This Link must return a transformation matrix (see : https://github.com/Phylliade/ikpy/blob/master/src/ikpy/link.py#L13).

Your transformation matrix is a homogeneous coordinate matrix representing your joint transformation. In the case of a leg, you can use the axis_tranformation_matrix from https://github.com/Phylliade/ikpy/blob/master/src/ikpy/geometry_utils.py#L61.

In order to get started you can also have a look at already-existing human models, in URDF. For example: https://github.com/baxter-flowers/human_moveit_config/blob/master/urdf/xacro/human_leg.urdf.xacro

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